The president and all 50 governors have declared health emergencies to counteract the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19). While researchers race to develop vaccines, officials are implementing physical distancing, including orders to stay at home, restricting travel, and closing nonessential businesses (see eFigure in the Supplement). To limit cross-border spread, more than a dozen states have issued mandatory quarantines for interstate travelers. Some models suggest physical distancing would have to persist for 3 months to mitigate the peak effects on health systems and could be required on an intermittent basis for 12 to 18 months.1 What legal powers do governments have? What is the role of the courts? How can public health be balanced with personal and economic rights?